Delay Control Research Articles

A Performance Analysis of a Two Way Stop Control (TWSC) Intersection under Mixed Traffic Conditions

Intersections are road traffic infrastructure on highways installed to help settle directional movement that could result in conflict while vehicular trips are made. Evaluation of the challenges faced by different automobile users at the Araromi junction (A three Leg at-grade Intersection) located in Akure is the main objective of this paper. To achieve this objective, traffic flow data were collected on the spot by video recording and then the data were manually counted. While, the highway Capacity manual 2010 methodology was adopted to analyse The entry flow rates, Potential Capacities, Movement Capacities, Movement Control Delay, Approach Intersection Control and 95th Percentile Quene Length of the intersection. Findings shows that an average entry flow rate of 357 pc/h occurs for all the legs of the intersection, the North bound left turning movement of the intersection was not within the allowable limit, the average potential capacity by lane for the intersection is 445 pc/h, and the average movement capacity by lane 473 Pc/h, the various legs of the intersection has a level of service of ‘A’ and ‘C’ except the left turning minor street movement that has an ‘F’ LOS. Due to the influence of high traffic flow around the intersection, the analysis of the real-time traffic flow results reveals the need to diverge the high right turning movement into other route to cater for low left turning movement causing delay and poor LOS and a need to introduce Signal on the intersection in other to improve on her functionality.

Paper-based microfluidic chips for wide time range fluid control based on knife crafting and laser cutting

In recent years, paper-based microfluidic chips have emerged as a promising microfluidic platform due to their simplicity, low cost, portability, and ease of fabrication. They have been applied in various fields such as biological analysis, environmental monitoring, and medical diagnostics. However, the current paper-based chips made of nitrocellulose membrane still can be improved in liquid flow rate control. To address these issues, a novel paper-based microfluidic chip is designed to control liquid in a wide time range, and the liquid delay and acceleration control are realized by laser cutting and knife crafting respectively. Microfluidic chip’s hydrophobic boundaries can be manufactured in a one-step process using laser cutting, taking less than 10 seconds. Additionally, the structural parameters of microgrooves, which have a significant impact on flow rate, can be precisely controlled using a scalpel-based cutting platform. This enables efficient and consistent microgroove processing. Furthermore, experimental optimization of laser cutting and knife crafting parameters is performed, along with an exploration of factors influencing the delay and acceleration effects in the chip structures. The effectiveness of these processing methods is validated through practical applications. In summary, this study realizes a wide time range fluid control in paper-based microfluidic chips, which can achieve delay and acceleration in the range of −55.6% to +828.3%, thus expanding the application range of paper-based microfluidic chips.

[formula omitted] sampled-data load frequency control with time-varying delays considering delay compensation

Time delays in load frequency control (LFC) systems may deteriorate the control performance or cause instability. How to mitigate such adverse effects of delays in a simple but effective way is worth investigating and motivates this work. For sampled-data LFC systems with time-varying delays, this paper introduces two delay compensation techniques, namely linear and division-based methods, aimed at enhancing the robustness of LFC. A stability criterion based on H∞ is derived to ensure LFC system stability under delay compensation. Building upon this criterion, we propose an H∞ controller optimization method to tune delay compensation controller gains offline by searching for a minimum H∞ disturbance attenuation level and effectively segmenting the geometric region formed by the delays. The effectiveness of the proposed delay compensation techniques and the controller design method is verified via numerical examples on an LFC system with both generation unit and energy storage participation.

An Improved Voltage Control Method for EAST Fast Control Power Supply

The Experimental Advanced Superconducting Tokamak (EAST) fast control power supply (FCPS) is an important device for controlling the vertical displacement of plasma during the nuclear fusion power generation process, adopting a multiple H-bridge invertor branch parallel operation structure to output total current. At the beginning of each shot of plasma discharge, FCPS works in open-loop voltage control mode (VCM) or closed-loop current control mode (CCM) determined by the plasma control system to output current for exciting the load coil, to achieve plasma vertical displacement control. VCM has the characteristics of fast dynamic response speed but poor consistency of branch current and insufficient branch current control accuracy and stability because of open-loop control. CCM has the characteristics of high branch current control accuracy but poor dynamic response and robustness because of control delay and control parameters determined based on engineering experience. To achieve fast and robust control, an improved voltage control method (IVCM) is proposed by combining the advantages of VCM and CCM. In the beginning of establishing the output current, FCPS operates in VCM, and rapid establishment of the output current is ensured. After the output current rapidly increases to the critical value, closed-loop current control is added to VCM to ensure the accuracy of output current control. In closed-loop current control, linear super-twisting sliding mode control is designed to achieve fast and robust control, ensuring good consistency and fast dynamic response performance of each branch current. Simulations and experiments verify that the designed IVCM has better compatibility characteristics in output current stability, control accuracy, and consistency of each branch current compared to VCM.

Automated Plant Disease Detection Using Deep Learning

Traditional methods of diagnosing plant diseases are mainly based on expert diagnosis which easily causes delay in crop disease control and crop management. Due to the problems of many target areas and similar target types in the process of plant disease detection, the identification accuracy and speed are required to be high. Therefore, it is necessary to optimize and improve the existing methods (CNN, RCNN, Fast RCNN, Faster RCNN, and SSD) to meet the detection needs. So, we came up with a deep learning-based approach to identify the plant leaf diseases and classify the diseases using an object detection model called YOLO. There are different versions of YOLO, proposed in recent times, in that YOLOv5 model is considered one of the best models and the other is the recent version, YOLOv8 which was proposed in 2022. So, in this paper we compared the two models of YOLO, YOLOv5 and YOLOv8 on the same dataset, and found that for the dataset used the YOLOv5 model was found to be the better model with a mAP of 0.641, while the YOLOv8 model has mAP of 0.516. This study proposes that the YOLOv5 model is suitable for plant disease identification tasks by comparing it with the latest version of the YOLOv8 model which was proposed in 2022. To make the YOLO model to be better it can be optimized and the transfer learning ability of the model can be used to expand the application scope in the future. Keywords— Deep Learning, CNN, RCNN, Fast RCNN, Faster RCNN, SSD, YOLO, mAP, Transfer Learning, Disease Classification, Detection.

Inkjet Printing on Hydrophobic Surface: Practical Implementation of Stacked Coin Strategy

While inkjet printing on many hydrophilic surfaces is achieved through control of drop spacing and droplet deposition delay, the same for hydrophobic substrates proves challenging. Low surface energies of hydrophobic surfaces prevents intact and uniform lines of low‐viscosity ink to form. In this article, the stacked coin printing strategy used for hydrophilic surfaces, is adapted for hydrophobic surfaces. Stacked coin morphology is seen when droplet deposition time between two sequentially deposited droplets is longer than the evaporation time of the first droplet. On hydrophobic surfaces, the parameter window for successful printing is smaller than on hydrophilic surfaces, thus an investigation is needed to implement this methodology. Experiments were conducted using an inkjet printer with variable stage speed and stage temperature. Silver nanoparticle ink was used to print on Teflon–AF substrates. We identified the following regimes: isolated droplets, isolated multi‐droplets, broken line, true stacked coin, and delamination. The relationship between substrate temperature, drop spacing, and droplet deposition delay controls the occurence of each regime. In this study, 180 °C was identified as the critical temperature for instantaneous drying of the studied ink, and a maximum drop spacing of 20 μm to print continuous lines.

Dynamical analysis of a stay cable with a nonlinear energy sink and time-delayed feedback control

Stay cables exist commonly in engineering and can exhibit sustainable and large vibrations under external excitations. The unexpected oscillations always lead to the fatigue and damage of structures, resulting in the economical loss. This paper studies the vibration control of a stay cable system with a nonlinear vibration absorber and time delay control. The governing equations of motion of the stay cable system under harmonic excitations are given. The stability and different bifurcations of the trivial equilibrium point of the system are analyzed. The bifurcation diagrams with respect to the control parameters are illustrated. The frequency responses of the forced system are obtained by using the harmonic balance method. Numerical simulations are performed to validate the obtained results and various dynamical phenomena are shown, such as the multi-period oscillations, quasi-periodic responses and chaotic motions. The effects of the time-delayed feedback control on the nonlinear dynamics and vibration reduction of the system are extracted. It is shown that the proper values of the time delay and feedback gain can improve the vibration reduction performance of the system, such as the suppression of the resonance peaks and elimination of the complex responses.

A Series Impedance Reshaping Control Method Considering PLL Dynamics for Grid-Connected Inverters Under Weak Grid Conditions

Grid-connected inverters are the key part in renewable energy power generation systems. Usually, phase-locked loop (PLL) is adopted in grid-connected inverters to achieve synchronization. However, prior-art works have revealed that the negative resistance behavior in the low-frequency band caused by PLLs may lead to system instability under weak grids. In this paper, first, a comprehensive small-signal output impedance modeling of the LCL-filtered single-phase grid-connected inverter is derived for stability analysis, where the digital control delays and PLL dynamics have been taken into account. Then, a simple but effective virtual series based impedance reshaping method is proposed. With that, the inverter system can operate stably even under a very weak grid (e.g., short-circuit ratio (SCR) is as low as 1.2). Compared with the traditional grid impedance compensation by virtually increasing grid resistance or reducing the grid inductance, the proposed method does not require grid impedance estimation and is robust against system parameter variations. Thus, its feasibility is improved. Finally, experimental tests are carried out on a single-phase 5-kW prototype, validating the effectiveness of the proposed scheme.

Exponential stabilization of the class of the switched systems with mixed time varying delays in state and control

This paper presents the problem of exponential stabilization of switched systems with mixed time-varying delays in state and control. Based on the partitioning of the stability state regions into convex cones, a constructive geometric design for switching laws is put forward. By using an improved Lyapunov–Krasovskii functional in combination with matrix knowledge, we design a state feedback controller that guarantees the closed-loop system to be exponentially stable. The obtained conditions are given in terms of linear matrix inequalities (LMIs), which can be effectively decoded in polynomial time by various computational tools such as the LMI tool in MATLAB software. A numerical example is proposed to illustrate the effectiveness of the obtained results.

The Feasibility and Operational Performance of Implementation Median U-turn Intersections: A CRITIC Method

Currently, a growing number of cities are adopting the Median-U-Turn (MUT) intersection design to enhance road capacity and traffic efficiency. The critical question in selecting the right intersection design is how significantly the implementation of MUT can enhance intersection performance, focusing on three key aspects: intersection efficiency, capacity, and the environmental impact of the design. To address this question, an evaluation of operational performance under various prevailing conditions (roadway and control) was conducted using VISSIM, a microscopic simulation platform. This evaluation involved five scenarios: conventional intersections (with increased cycle length, grade separation with a signalized at-grade intersection, grade separation with a roundabout), MUT, and signalized crossover MUT at a dense urban arterial intersection in Amman, Jordan's capital. The performance was compared using several metrics: average control delay, number of stops, average travel speed and time, average stopped delay, Carbon Monoxide (CO) emissions, fuel consumption, and vehicle safety. The Criteria Importance Through Intercriteria Correlation (CRITIC) technique was subsequently used to select the optimal design. The findings indicate that the existing intersection configuration is the least effective, while the MUT with signals at the crossing U-turn points is the most efficient solution.

Controllability of time-varying fractional dynamical systems with distributed delays in control

Abstract The objective of this study is to assess controllability results in the realm of Caputo fractional derivatives, specifically focusing on time-varying linear and nonlinear fractional dynamical systems with distributed control delays. In the setting of a linear system, using the Grammian matrix's positive definiteness makes it possible to ascertain both the necessary and sufficient conditions. It is possible to determine, for nonlinear systems, the sufficient conditions for the presence of a solution by making use of the Schauder fixed point theorem. In addition to that, the paper discusses the controllability of a nonlinear integrodifferential system for a particular case. A few examples and the graphs that correspond to them are shown here to make it easier to conceptualize the conclusions of the theoretical discussion.

To Drain or Not: Drainage Procedures Remain a Central Tenet of Management of Infected Collections in Acute Pancreatitis.

Recent literature advocates for delayed or avoidance of catheter drainage of infected peri-pancreatic collections (IPCs) in acute pancreatitis (AP). This may not be realistic for patients at academic centers, many of whom are critically ill. We retrospectively reviewed 72 patients admitted to our institution from 2016-2021 with AP and IPCs. 34.7% had a Bedside Index of Severity in Acute Pancreatitis (BISAP) score ≥3, and 56.9% had a Balthazar score of E. 65.3% were admitted to the ICU, 51.4% experienced respiratory failure, and 47.2% had acute renal failure. In-hospital mortality was 9.7%. Catheter-based drainage alone was the most frequent intervention. Only 8 individuals did not undergo any drainage. Individuals with severe AP complicated by IPCs are critically ill. Avoidance or delay of source control could lead to significant morbidity. Until further research is done on this population, drainage should remain a central tenet of management of IPCs.

DCCS: A dual congestion control signals based TCP for datacenter networks

As cloud computing advances, datacenter networks (DCNs) face unprecedented pressure due to the increasing prevalence of high bandwidth and low delay applications. Current reliable transmission protocols such as TCP harness packet loss, network delay, and Explicit Congestion Notification (ECN) for congestion control, aiming to maintain low latency and high throughput. We investigate the efficacy of ECN-based protocols against incast congestion in one-hop networks and delay-based protocols for maintaining low end-to-end delay in multi-hop networks, at the expense of throughput fairness. Thus, we introduce a novel TCP protocol, Dual Congestion Control Signals (DCCS), merging ECN and delay signals for a broader congestion control mechanism. DCCS effectively handles burst traffic, prevents packet loss, ensures low end-to-end delay, and resolves throughput unfairness by determining a precise minimum round-trip time (RTT) for each flow through a drain signal. Simulations on ns-3 confirm that DCCS surpasses ECN-based (i.e., DCTCP), delay-based (i.e., DC-Vegas and Swift), and hybrid-based protocols (i.e., EAR) in fat-tree topology under realistic workload, cutting down Flow Completion Time (FCT) by 3.8%–20.5%. This substantiates DCCS’s competency in providing high-quality service for DCNs.

Adaptive Backstepping Time Delay Control for Precision Positioning Stage with Unknown Hysteresis

Piezoelectric-actuated precision positioning stages are widely used in high-precision instruments and high-end equipment due to their advantages of high resolution, fast response, and compact size. However, due to the strong nonlinearity of hysteresis, the presence of hysteresis in piezoelectric actuators seriously affects the positioning accuracy of the system. In addition, it is challenging to identify the model parameters for hysteresis. In this paper, an adaptive backstepping time delay control method is proposed for piezoelectric devices system with unknown hysteresis. Firstly, the Bouc–Wen model is used to describe the hysteresis characteristics, and the model is interpreted as a linear term and a bounded uncertain hysteresis term. Then, the time delay estimation technique is used to estimate the hysteresis term of the Bouc–Wen model online, and the unknown parameters of the system and hysteresis model are obtained through adaptive updating laws. Furthermore, the stability of the control scheme is proved based on Lyapunov stability theory. Finally, the effectiveness and superiority of the proposed control scheme are demonstrated by comparing it with two typical hysteresis compensation control algorithms through three different sets of input signals.

Assessing the efficacy of the Stop OsteoARthritis (SOAR) program: A randomized delayed-controlled trial in persons at increased risk of early onset post-traumatic knee osteoarthritis

ObjectiveAssess the efficacy of an 8-week virtual, physiotherapist (PT)-guided knee health program (SOAR) to improve knee extensor strength in individuals at risk of post-traumatic knee osteoarthritis (PTOA). MethodIn this superiority, randomized delayed-control trial, persons aged 16-35 years, 1-4 years after a self-reported knee joint injury were randomly assigned (1:1) to receive the SOAR program immediately (experimental group) or after a 9-week delay (control group). SOAR includes 1) one-time Knee Camp (virtual PT-guided group education, knee assessment, 1:1 exercise and physical activity goal-setting); 2) Weekly personalized home-based exercise and physical activity program with tracking; 3) Weekly 1:1 PT counseling (virtual). The primary outcome was change in isokinetic knee extensor strength (baseline to 9-weeks). Additional outcomes included change in self-reported knee-related quality-of-life (QOL), self-efficacy, self-management and kinesiophobia, and physical activity (accelerometer) at 9 and 18-weeks. Linear regression models estimated the effect of the 8-week intervention at the primary endpoint (9-week). Results49 of 54 randomized participants completed the study (91%). Participants were a mean±SD age of 27±5.0 years, and 2.4±0.9 years post-injury. No mean between group differences for the primary (0.05; 95%CI: -0.10,0.19) or other outcomes were seen at 9 weeks except for greater improvements in perceived self-management (Partner in Health Scale; 11.3/96, 95%CI: 5.5,17.1) and kinesiophobia (Tampa Scale of Kinesiophobia; -4.4/33, 95%CI: -7.0,-1.8). ConclusionFor active persons with elevated risk of PTOA, an 8-week SOAR program did not change knee-related strength, QOL, self-efficacy, or physical activity, on average, but may benefit the ability to self-manage knee health and kinesiophobia.

Estudio comparativo del control de nuestros pacientes diabéticos tipo 2 antes y después del confinamiento producido por la pandemia COVID-19

ObjectiveTo assess the impact of the alterations of continuity of care on diabetic patients in our health department during the confinement that caused the pandemic. Check whether or not confinement mean tan alteration in the degree of control of our type 2 diabetic patients. Know whether our diabetic patients were adequately coontrolled before the pandemic began. Know if the pandemic has led to a deterioration in its degree of control. Subject and methodRetrospective study between the years 2019 and 2020 of type 2 diabetic patients in our health area. Through the “Alumbra” application of our health area, a random sample of our patients diagnosed with type 2 diabetes from 18 to 100 years of age was obtained. The patients was informed if they wanted to enter the study and after the patient´s express consent, the patient was asked about their lifestyle, habits and a review of the medical history was carried out with the data recorded before the confinement (year 2019) and during the months of confinement of 2020. ResultsThere were 882 patients (88.28%) with HbA1c determinations in 2019 with a mean of 7,08. There were 800 patients (88.98%) with HbA1c deteminations in 2020 with a mean of 7,02. There was a reduction in alcohol, tobacco and soft drink consumption habits, but there was also a reduction in physical exercise (33% to 22%) and is following a diabetic diet (34% to 24%). In the sample analyzed, there was a reduction in a alcohol consumption from the data obtained in 2019 to those obtained in 2020 (22% to 13%). There was an increase in obesity, which goes from 77,7% to 90,4%. It is observed that there is no change in the percentages in pathologies such as dislipemia, atrial fibrilation, osteoarthritis, and stroke. ConclussionThe consequences associated with the pandemic on health are worrying, the decrease in acute consultation, preventive activities and the delay in controls for chronic patients will have a profound impact on the psychological and socioeconomic well being of populations. The holistic view of the Primary Care and the need to strengthen and rethink the system to increase its effciency are of particular importance.

Adaptive cruise control design for collision risk avoidance

With advanced technologies such as perception and automatic control, automated vehicles (AVs) are gradually replacing human-driven vehicles (HDVs). They will become a significant component of transportation systems. As the crucial longitudinal control model for AVs, the existing adaptive cruise control (ACC) model faces challenges such as poor linear stability and compromised safety. To solve the problem, this paper proposes an adaptive cruise control model to avoid collision risk. First, the delay-considerate collision risk control strategy (DCRCS) is developed to consider vehicles' perception and control delay. Then, a proposed adaptive cruise control (PACC) model is designed by incorporating DCRCS into the ACC model based on the control gain coefficient. Finally, the effectiveness of the PACC model is discussed and analyzed in terms of stability, safety, efficiency, energy consumption, and pollutant emissions through a combined approach of theoretical analysis and simulation experiments. The result shows that (1) compared to the classical ACC model, the PACC model demonstrates significant improvements in system stability, reduced safety risks, enhanced efficiency, and decreased energy consumption and pollutant emissions. These enhancements are observed when the control gain coefficient is set to a positive value. (2) The equilibrium speed minimally influences the effectiveness of the PACC model. Under varying speed conditions, the PACC model consistently maintains stable performance. (3) The effectiveness of the PACC model is closely related to the selection of the control gain coefficient. Considering the effects of the control gain coefficient on stability, safety, efficiency, energy consumption, and pollutant emissions of the PACC model, the optimal range for the control gain coefficient is in the range of [0.8, 1.0]. In summary, compared to the classical ACC model, the PACC model exhibits outstanding performance in various aspects. It provides theoretical support for the longitudinal control of AVs in the future.

Ultra-fast tuning of neural network controllers with application in path tracking of autonomous vehicle

Neural network (NN) controllers have shown great potential in solving complex control or decision-making tasks. However, most of the NN controllers either rely on the availability of large datasets or require dense interactions with the environment, which hinders their application in real systems. In this paper, we introduce a model-based reinforcement learning (MBRL) algorithm, aimed at realizing ultra-fast tuning of deep NN controller from a small sample set of real-world data. The algorithm uses Gaussian processes (GPs) to model the unknown dynamics of real system and updates controller parameters through stochastic gradient descent. By using particle-based method for long-term predictions, the algorithm can easily incorporate online state estimators and filters into controller learning, which is conductive to learning from systems with partially measurable states and stochastic control delay. We apply the algorithm to calibrate a deep NN controller for the path tracking of a full-size autonomous vehicle (AV). Simulation and field test results show that the deep NN controller can be well calibrated after only one interaction with the environment and can achieve similar tracking performance to optimization-based methods such as nonlinear model prediction control (NMPC) in various test scenarios by combining with a feed-forward pure pursuit (PP) controller.

Optimum Control Wind Power Installations Being Subjected to Ice Formation on Wind Wheel Blades Within Wind Electrc Station Structure

On the basis of the analysis of wind electric unit control with preliminary installation of blades at a required angle according to an estimation of the drive pitch engine start timesubjected toice formation on wind wheel blades to minimize the wind turbine rotor angular speedtransient time, that promotes wind wheel rotation speed stability under the conditions of incomplete wind speed and the electric loadinginformation, that may change significantly with time, the criterion of access time to the of bladeposition control devicefrom the proposed and basic methods of control is established. The program module towind power automation control within thewind electric stationstructure is developed, providing relevantsystem preparation for external actions due to ice formation on blades wind wheel at different operation modes of power unit,that showedangular speed increase of a wind turbine rotor during winter time thus demanding more energy of a wind stream (14m/s) in comparison with the spring and autumn period (11.1m/s).Therefore, ice formation on wind wheel blades slows down wind wheel rotor rotation. Hence, the offered control method efficiency during winter time to avoid control delay is shown byrotation speed increase of a wind turbine rotor towards can be realizedforwind speeds exceeding 13m/s. The improved software control unit of wind power installation within the structure of wind power station based on the power unit operation modes provides: «Summer mode» - electric power generationunder favorable environment conditions; «Winter mode» - electric power generation under ice formation on blades wind wheel.

Multi-segment droop control and optimal parameter setting strategy of wind turbine for frequency regulation

Traditionally, virtual inertia is used as the control strategy for wind turbines when participating in frequency regulation. However, it has inherent defects in measurement error amplification due to the frequency differential. Also, when control delay of wind turbines is taken into consideration, virtual inertia is essentially a fast power response, just the same as droop control. Hence, considering the adaptability of droop control, it is valuable to explore a novel droop control method without virtual inertia, as the frequency response model of wind turbines. For this reason, a multi-segment droop control strategy is proposed to provide a reliable frequency regulation model for wind turbines that can be broadly applied to other inverter-based power sources. Firstly, based on the extended system frequency response model, a differential equation including piecewise time-varying coefficients is established, and the analytical expression of the frequency response is obtained using the impulse function balancing principle and the integration by parts algorithm. Subsequently, based on analytical expression, the performance of the presented strategy is theoretically analyzed via comparison with virtual inertia control, and the conclusion that the presented multi-segment droop control has better frequency regulation performance can be got. Furthermore, to achieve optimal frequency regulation performance, a Lagrangian function is established to determine the optimal parameters of the proposed control strategy. Finally, the performance of the proposed strategy was verified in a two-area system model constructed on MATLAB/Simulink. Results show that the proposed multi-segment droop control has better frequency regulation performance.